The Advantage of Increased Resolution in the Study of Quasar Absorption Systems

Abstract

We compare a new R = 120,000 spectrum of PG1634+706 (z_QSO = 1.337,m_V = 14.9) obtained with the HDS instrument on Subaru to a R = 45, 000 spectrum obtained previously with HIRES/Keck. In the strong MgII system at z = 0.9902 and the multiple cloud, weak MgII system at z = 1.0414, we find that at the higher resolution, additional components are resolved in a blended profile. We find that two single-cloud weak MgII absorbers were already resolved at R = 45,000, to have b = 2 - 4 km/s. The narrowest line that we measure in the R = 120, 000 spectrum is a component of the Galactic NaI absorption, with b = 0.90+/-0.20 km/s. We discuss expectations of similarly narrow lines in various applications, including studies of DLAs, the MgI phases of strong MgII absorbers, and high velocity clouds. By applying Voigt profile fitting to synthetic lines, we compare the consistency with which line profile parameters can be accurately recovered at R = 45,000 and R = 120,000. We estimate the improvement gained from superhigh resolution in resolving narrowly separated velocity components in absorption profiles. We also explore the influence of isotope line shifts and hyperfine splitting in measurements of line profile parameters, and the spectral resolution needed to identify these effects. Super high resolution spectra of quasars, which will be routinely possible with 20-meter class telescopes, will lead to greater sensitivity for absorption line surveys, and to determination of more accurate physical conditions for cold phases of gas in various environments.

arXiv commentTo appear in AJ. Paper with better resolution images available at http://www.astro.psu.edu/users/anand/superhigh.AJ.pdf

References in corpus (21)

• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems: Physical conditions in the neutral gas
• The Population of Weak Mg II Absorbers I. A Survey of 26 QSO HIRES/Keck Spectra
• CII* Absorption in Damped Lyman Alpha Systems: (I) Star Formation Rates in a Two-Phase Medium
• QSO Absorbing Galaxies at z<~1: Deep Imaging and Spectroscopy in the Field of 3C 336
• The Population of Weak MgII Absorbers. II The Properties of Single-Cloud Systems
• The Physical Conditions of Intermediate Redshift MgII Absorbing Clouds from Voigt Profile Analysis
• Low and High Ionization Absorption Properties of Mg II Absorption-Selected Galaxies at Intermediate Redshifts. II. Taxonomy, Kinematics, and Galaxies
• The Kinematics of Intermediate Redshift Mg II Absorbers
• On the variation of the fine-structure constant: Very high resolution spectrum of QSO HE 0515-4414
• The Kinematic Composition of MgII Absorbers
• High Resolution STIS/HST and HIRES/Keck Spectra of Three Weak MgII Absorbers Toward PG 1634+706
• Detection of Warm and Cold Phases of the Neutral ISM in a Damped Ly-alpha Absorber
• Low-column density gas clumps in the halo of the Milky Way
• The Absorption Signatures of Dwarf Galaxies: The z=1.04 Multicloud Weak MgII Absorber toward PG 1634+706
• The Absorption Signature of Six MgII-Selected Systems Over 0.5<z<0.9
• A Quadruple-Phase Strong Mg II Absorber at z~0.9902 Toward PG 1634+706
• Models of Five Absorption Line Systems Along the Line of Sight Toward PG0117+213
• A Survey of Analogs to Weak MgII Absorbers in the Present
• A survey of weak MgII absorbers at redshift <z>=1.78
• The Complex Interstellar Na I Absorption toward h and Chi Persei
• Mini High Velocity Clouds

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